have been enumerated, the ROM then tries to figure out what Drive (from its Drive Queue, which contains pointers back to the driver used for accessing it), first checking the floppy, checking the selected Startup Disk stored in PRAM, and eventually enumerating the drive queue looking for a valid HFS signature and valid boot blocks that point to the system file. After all slots, SCSI ID's, partitions, etc. The SCSI Manager then uses the device driver to load the partition map, and adds each partition to the Drive Queue. Subsequent access to the device is handled through that device's device driver. SCSI Manager loads the driver into RAM, and opens the driver. The first sector contains the Driver Descriptor Record, which contains sector size of the device, location & length of the device driver(s), etc. My understanding is: when a SCSI device is detected in the SCSI chain by SCSI Manager, it issues a SCSI Read of sector 0. The Start Manager of IM: OS Utilities along with IM: Devices SCSI Manager section has some relevant information on this. Click to expand.I was curious so I looked into this a bit more, and here's what I found.
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